Sarcoidosis May Be Associated with Specific Infectious Agents, Review Finds

Sarcoidosis may be associated with infections by Propionibacterium acnes (associated with the skin condition of acne) and mycobacteria (tuberculosis bacteria), according to a new study.

The study, “Is There Any Association Between Sarcoidosis And Infectious Agents?: A Systematic Review And Meta-Analysis,” was published in the journal BMC Pulmonary Medicine.

Sarcoidosis may be triggered by more than one factor, including infectious and noninfectious agents.

“Currently, the focus is on infectious agents, especially species of Mycobacterium and Propionibacterium,” the authors wrote in their report. “Other infectious agents have been investigated with inconclusive or conflicting results, such as Borrelia burgdorferi, Rickettsia helvetica, Chlamydia pneumoniae, viruses, fungal infections, and Leishmania species.”

Now, researchers reviewed all original work published from 1980 to 2015 on the subject, and selected 58 research articles to include in their analysis. These studies referred to patients with a well-documented diagnosis of sarcoidosis and included case-control reports of the presence of microorganisms in samples of patients with sarcoidosis, using culture methods or molecular biology techniques.

The analysis suggested a causal association between the diagnosis of sarcoidosis and infection by P. acnes and mycobacteria.

However, the authors found no association between sarcoidosis and infection with certain pathogens that had previously been suggested as triggering factors for the disease, namely Borrelia, HHV-8, Rickettsia helvetica, Chlamydia pneumoniae, Epstein-Barr virus and retrovirus.

“The present [study] is the first to evaluate all infectious agents proposed to be associated with sarcoidosis and involving more than 6,000 patients in several countries,” the authors wrote.

“The results point to a [causal] link between P. acnes and sarcoidosis … Also, almost one quarter of sarcoidosis patients show the presence of mycobacteria within the lesions. The associations are fairly specific, since P. acnes … and mycobacteria … were significantly increased in sarcoidosis patients, while Borrelia… and HHV-8 … were not associated with sarcoidosis, contrary to previous investigations,” they wrote.

The report has some limitations, including the fact that the studies refer to patients from various countries around the world and were differently designed and conducted. However, the authors believe they have found evidence that sarcoidosis may be associated with more than one infectious agent.

“This meta-analysis suggests that some infectious agents can be associated with sarcoidosis,” the team wrote. “What seems clear is that more than one infectious agent might be implicated in the pathogenesis of sarcoidosis; probably the patient’s geographical location might dictate which microorganisms are more involved. Future investigations and more clinical trials are need to bring these evidences to a more global level.”